ldap_auth.pl for qmail

ldap_auth.pl is a Perl program that is a substitute for Dan Bernstein's checkpassword. It uses the same error codes and interface as checkpassword. But, it authenticates against an LDAP server with options specified within the program.

Why? qmail-LDAP is a very robust qmail+LDAP installation. It's a lot more than I needed. I just wanted to authenticate people to an already existing LDAP server. I didn't want to interact with LDAP in any other way. qmail-LDAP isn't made for that. So, I wrote this simple program that does one thing, authenticates against an LDAP server.